Keep It Simple Stupid. This catchy little acronym (KISS) and phrase applies to so many things in life, including web sites.
That is not to say that a web site cannot have loads of great content and relevant information pertaining to your business. It should. But by KISSing your website, you want to make sure that:
1) you don't bore your visitors
2) you don't overwhelm your visitors.
Unless you are some type of educational site (and even then I'd recommend being careful on this one), you want to make sure that what you have to tell your visitor is clear and concise. Use bullet points rather than long stretches of paragraphs. Don't bore them into leaving your site. Entice them into calling or emailing you.
You also don't want to overwhelm your visitors with too much 'stuff' - flash, scrolling text, tons of boxes and pictures. While you may think having Flash on your website will really jazz it up, statistically speaking, most users press the 'skip intro' button on the opening page and never see the Flash...can sometimes be a waste of money, quite frankly.
As always, continue to provide great, relevant content on your website, but think about your audience when you do.